Abrasive wheels

ABSTRACT

An abrasive wheel is provided wherein coated abrasive segments are arranged annularly in interlocking pairs. Such interlocking makes it possible to assemble a greater number of abrasive segments in the wheel thus providing an abrasive wheel of improved performance.

United States Patent ['72] Inventor George L. Haywood [56] ReferencesCited Wham UNITED STATES PATENTS [2 P 2,808,689 10/1957 Thomson et a1.51/337 [22] ($1969 3 078 624 2/1963 Peterson 51/334 {45] Patented Aug,I971 [73] Assignee Norton Company Primary Examinerwilliam R. ArmstrongTroy, N.Y. Attomeys--Hugh E. Smith and Herbert LJGatewood [54] ABRASIVEWHEELS 7 Claims, 6 Drawhg lip.

[52] US. Cl. 51/334, ABSTRACT: An abrasive wheel is provided whereincoated 51 I337, 15,230 abrasive segments are arranged annularly ininterlocking [51] Int. CL 1324b 9/02 pairs. Such interlocking makes itpossible to assemble a [50] Field of Search 51/334, greater number ofabrasive segments in the wheel thus provid- PATENTEB M24192: 3500.861

52 PRIOR ART F'ls.6

NV NTOR GEORGE LfiAYwooo ABRASIVE WHEELS BACKGROUND OF THE INVENTION 1.Field of the Invention This invention relates to flexible abrasivewheels and to their method of manufacture.

2. Description of the Prior Art Flexible abrasive wheels, commonlyreferred to as Flap Wheels" and made up of a plurality of annularlyarranged coated abrasive segments, have found utility in a variety ofabrading operations. In certain instances, however, such abrasive wheelshave not been found totally satisfactory in their performance becausethey did not present the desired hardness or resistance of work surface.

The hardness or resistance of a Flap Wheel work surface is determined bythe number of segment ends available at the outer periphery. In general,the greater the number of ends, i.e., the number of flaps or abrasivesegments in a Flap Wheel, the greater is the resistance and hardness ofthe abrasive wheel work surface at any given wheel speed. Thus, the

. more abrasive segments in a Flap Wheel, the better it performs becausesuch presents a harder, more resistant work surface and more abrasivewipings can be given to a workpiece per rotation of a particular wheel.

For these reasons, it has been suggested heretofore to provide abrasivewheels with the greatest number possible coated abrasive segments.Generally, attempts to provide such wheels involve merely compressingthe segments together, sometimes mechanically, in closer relationship.However, one solution of which I am aware, disclosed in U.S. Pat. No.2,808,689, suggests making flaps thinner at the inner end portion. Toproduce this result, the abrasive face of the coated abrasive segment orflap is skived at the inner end. Although this permits in an abrasivewheel an increased number of flaps as compared with an abrasive wheelwhere the flaps have not been skived, there are certain problems anddisadvantages associated with the manufacture of such a Flap Wheel.

Skiving of abrasive segments so as to prevent any damage to theunderlying backing material is a difficult and time-consuming operationto perform. Moreover, it involves the extra handling of small workpiecesand the performance of an extra operation. All of these operationscontribute to increased costs in the manufacture of abrasive wheels.

SUMMARY OF THE INVENTION In accordance with the general aspects of myinvention, an abrasive wheel is provided having a working surface of improved hardness and resistance to deformation. This improvement isaccomplished by providing in the abrasive wheel coated abrasive segmentswhich are interlocked in pairs to provide a combined thickness of thebase edge less than the sum of the individual segment thicknesses. Suchreduction in thickness permits a greater number of coated abrasivesegments to be assembled in an annular ring of any given diameter.

Quite advantageously, the invention permits the manufacture of abrasivewheels with a larger total number of abrasive segments without requiringany additional processing steps to the present method of manufacture andwithout requiring any mechanical compacting device.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understoodby referring to the drawing in which like numerals refer to like partsin the various views and in which:

FIG. I is a partial cross-sectional view of a completed abrasive wheelin accordance with the invention, the coated abrasive segments beingshown in elevation for cleamess in illustration;

FIG.. 2 is afront elevation of one of the interlocking pair of abrasivesegments of the invention;

FIG. 3 is a front elevation of the other one of the interlocking pair; IFIG. 4 is a side elevation of an interlocking pair of coated .7

DETAILED DESCRIPTION OF THE INVENTION Turning now to the drawing, thereis disclosed in FIG. 1 thereof, in accordance with the invention, acompleted abrasive wheel 10. Coated abrasive segments 11, 12, havinginner or base edges l3, l4, and outer or working edges 15, 16 (FIGS. 2,3), assembled in interlocking pairs 17 (FIG. 4) in an annular row, forman inner cylindrical periphery l8 and an outer cylindrical periphery 19.

The assemblage of coated abrasive segments 11, 12, or flaps as they arecommonly called, is clamped between sideplates 20, 21. The sideplatesare held together and in contact with the abrasive segments by means ofarbor 22 which extends through axially aligned bores 23, 24 in thesideplates. The arbor is threaded at one end 25 to have screwed thereona nut 26. At the opposite end of arbor 22 is located spindle 27 by whichmeans arbor 22 can be connected to a drive means (not shown) forrotation of the abrasive wheel.

Each of the sideplates 20, 21 is provided with an annular protrusion orflange identified in FIG. 1 by reference numerals 28, 29. These flanges,as shown in FIG. 1, intrude into annular grooves 30, 31 formed bynotches 32, 33 and indentations 34, 35 when the coated abrasive segmentsare annularly assembled. The size of these notches and indentationsdepends upon the size segment; however, for purposes of illustration, anotch or indentation Ai-inch i rinch has been found satisfactory for a2-inch wide segment. The comers of the notches and indentations, ifdesired, may be slightly rounded.

At the inner periphery 18, the abrasive segments are bonded together byadhesive 36. This adhesive may extend over the entire inner periphery;however, in the practice of my invention, I have found it entirelysufiicient to provide adhesive 36 on the inner periphery only at theinterlocking portion of the segments as shown in the drawing. Theadhesive, which may be glue, or a curable synthetic resin compositionpreferably the latter, as desired, may be applied to the periphery bypainting. In addition to applying adhesive to the inner periphery,adhesive is generally also poured into the notches, and brushed, therebyproviding a bond with the sideplates. A desirable manner of applying acurable resinou adhesive, e.g., a syrupy liquid epoxide to the entireinner periphery, is disclosed in US. Pat. No. 2,842,902. Therein theadhesive is disclosed as applied by centrifugal casting. Regardless ofthe manner of application, the adhesive should be applied in sufficientquantity to penetrate between and firmly adhere together at their baseedges adjacent abrasive segments, thus providing a rigidified innerperiphery. Because of the structural features of the segments of myinvention, as hereinafter described, adhesive readily penetrates betweenadjacent segments thus providing for good anchorage.

Coated abrasive segment 11, as shown in FIG. 2 of the drawing, isprovided with cutout portion 37 extending away from base edge extendedas shown by reference numeral 13'. Cutout portion 37, open at base edgeextended 13', is defined by bottom edge 38, in the preferred aspect ofwhich is parallel to base edge extended and side edges 39, 40 connectingthe bottom edge to the base edge. Desirably, the side edges adjacent tobase edge extended 13', as shown in the drawing, are tapered outwardlytoward longitudinal edges 41, 42; however, these edges in the preferredembodiment are parallel to one another at their outer ends 43, 44. Inthe preferred embodiment of the invention bottom edge 38 extends nogreater distance from base edge extended 13 than an imaginary line(shown by dotted line 38') connecting together opposed notches 32, 33.Such line preferably bisects the notches. This feature lessens thechance of flap throw out" due to flexing during use.

' Cutout portion 37 desirably is centered between longitudinal edges 41,42 thereby providing a coated abrasive segment of symmetricalconstruction. However, it will be realized by those skilled in the artthat in abrasive wheels of greater width it may be desirable to have aplurality of cutout portions spaced equally along the base edge.

Coated abrasive segment 12, forming the other segment of theinterlocking pair, is provided, in the preferred embodiment, with twocutout portions 45, 46, which extend away from base edge extended, asindicated by reference numeral 14', and are spaced apart from oneanother, as shown in the drawing. Cutout portion 45-, as shown in FIG.3, is defined by indentation 34, bottom edge or shoulder 47 and sideedge 48. In the preferred embodiment bottom edge 47 is parallel to baseedge 14 and extends no farther distant from such edge than does bottomedge38 of coated abrasive segment 11. Side edge 48 of segment 12complements side edge 39 of segment llythus, in'its most preferredembodiment it tapers outwardly toward longitudinal edge 49. Cutoutportion 46 is the mirror image of cutout portion 45, like parts beingdefined by adding a prime to the reference numerals used in thedescription thereof.

As seen from the drawing (FIG. 3) spaced-apart cutout portions 45, 46define between them'a tablike portion 50. When coatedabrasive segments11, 12 are assembled together in pairs tablike portion 50 dovetails intocutout-portion 37 thus providing apair of segments which at the baseedge is less thick than the sum of the thicknesses of the individualsegments. v

Those skilled in the art will readily recognize that it is possible toprovide in abrasive segment 12 a multiplicity of tablike portions tocomplement the above-mentioned multiplicity of cutout portions inabrasive segment 1 l.

The coated abrasive segments, which can be die cut, or the like, fromany coated abrasive material, are arranged such that the abrasivesurfaces thereof extend in the same direction around the wheel structurewith the abrasive surface of one segment facing the back surface of theadjacent segment. If desired, however, coated abrasive segments may beused which are abrasively coated on both sides.

The following examples, which are given for purposes of illustrationonly and are not intended to be limiting of the inventiveconcept, willmore clearly illustrate the preferred embodiments of the invention.

EXAMPLE I Abrasive segments 51 (FIG. 6), conventionally used in themanufactured abrasive wheels,'were die cut from Grit 60 RESINALLMETALITEcloth. Each segment had a base edge 52, a working edge 53, andlongitudinal edges 54, 55. The segments were substantially rectangularin shape, as shown in the drawing being 2 inches (base edge) by 3%inches. Opposed notches 56, 57 (Vs-inch X li-inch) having slightlyrounded corners were provided in the longitudinal edges 54, 55 of theabrasive segments three-eighths inch from the base edge.

According to usual techniques these segments were then assembled in anannular fashion (see FIG. 5) by placing sideplate 21 (3 inches diameter)on a supporting surface (not shown) with flange 29 upright andthen-placing the segments by hand on the flanged sideplate in suchfashion that the matching flange projected into notch 56. Using onlyhand pressure, it was possible to assemble, on the average, only 181segments in an abrasive wheel.

In a similar fashion, coated abrasive segments were assembled in anannular row on flanged sideplates having diameters of 4 and 5 inches.The maximum number of segments which could be assembled by hand pressurewas, on the average, 250 and 319, respectively.

EXAMPLE 2 Coated abrasive segments ll, 12, having the shape" of thosesegments shown in FIG. 2 and 3 respectively, were di from the same typecoated abrasive cloth as th'e s'g example I. 9 I

Segments 11, having cutout portion 37 therei (FIGI Z) measured 2 inchesacross working edge 15. Longitudinal edges 41, 42 measured 3% inches.Opposed notches 32, 33 (%-inch X Vq-inch) having slightly roundedcorners were provided in the longitudinal edges three-eighths inch(bottom of notch) from base edge 13. Cutout-portion 37, of irregularshape, extended away from base edge 13, i.e., toward working edge 15,and was divided in half by an imaginary centerline dividing the abrasivesegment 11 laterally into two equal parts. The cutout portion, open atbase edge 13 of the segment, as indicated in the drawing, was defined bya bottom edge parallel to the base edge. The bottom edge wasthree-eighths inch from the base edge and extended laterally for adistance of one-fourth inch on each side of the imaginary centerline. Atthat point side edges extended perpendicular thereto and toward baseedge 13. These side edges at a distance from the base edge of one-eighthinch, taper outwardly at an angle of about 60. Thus cutout portion wasprovided at the base edge with an opening of three-fourths inch.

Segments 12, having base edge 14, working edge 16, and longitudinaledges 49, 49' were die cut so as to provide at the base edge twospaced-apart cutout portions defining a tablike portion 50 (FIG. 3). Thesegment measured 2 inches (working edge) X 3%. Tablike portion 50measured three-fourths inch along base edge I4 and was divided in halfby an imaginary centerline which divided the coated abrasive segment 12into two equal parts. The tablike portion tapered inwardly (60) from thebase edge such taper terminating about one-eighth inch distancetherefrom. At that point, side edges parallel with respect to oneanother were extended perpendicular to the base edge terminating atshoulders 47, 47' parallel with the base edge and three-eighths inchdistance from this edge. These shoulders extended approximately one-halfinch joining at their ends with indentations (Vi-inch X 84-inch)provided in longitudinal edges 49, 49'. Such indentations correspondwith notches 32, 33 in segment 1 1.

Die cut segments 11, 12 were matched together in complementary pairs 17(FIG. 4), the tablike portion 50 interlocking with cutout portion 37.These pairs of segments were then assembled by hand in an annular row ona flanged end plate 21, as described in example I.

1 cut in As indicated in the table below, with the segments of myirivention, an abrasive wheel can be produced having a substantialincrease in the number of coated abrasive segments.

The improved performanceof abrasive wheels produced in accordance withmy invention is shown in the following comparative test.

EXAMPLE 3 Abrasive wheel segments, as in examples 1 and 2, wereassembled in annular fashion, by hand, on a 5-inch diameter flanged endplate. After assembly, a liquid curable adhesive having the compositionhereinafter described was applied as follows: The adhesive compositionwas brushed onto the inner periphery (in the case of wheels utilizingabrasive segments according to the invention, the adhesive compositionbrushed onto the periphery of the dovetailed segments formed a beadabout half the width of the adhesive layer shown by reference numeral36); next, the adhesive composition was poured and brushed into theannular groove defined by the notches in the sides of the segments. Asecond flanged end plate was positioned such that its flange fitted intothe annular groove. The abrasive wheel was then turned over, the firstpositioned end plate was removed and adhesive was again applied to theinner periphery (bead forming other half of adhesive 36 shown in thedrawing in the case of segments according to the invention). Adhesivecomposition was then poured into the groove defined by the notches afterwhich the end plate was repositioned. After about 5 hours at roomtemperature, the adhesive composition (end plates compressed by arbor)was cured and the abrasive wheel was ready for use. The adhesivecomposition was observed to be penetrated between the segments of theinvention at their base edges thus bonding the segments together andforming a rigidified inner periphery.

RESIN MIX COMPONENTS WEIGHT (LBS.)

Epon 815 23% (an epoxy resin which is the condensation product ofepichlorohydrin and bisphenol A) Santocel (silica aerogel) ADHESIVECOMPOSITION COMPONENTS WEIGHT (GMS.)

Resin Mix I Diethylene triamine 20 A 2-inch ring was cut from a 6-inch[.D. carbon steel pipe. This ring, suitably mounted for rotation, wasrotated at a surface speed of 1 feet per minute (s.f.p.m.).

The abrasive wheels, rotating at a surface speed of 4,580 s,f.p.m., wereurged in grinding contact with the steel ring using 5 lb./inch widthdead weight pressure.

The abrasive wheel having interlocking segments in accordance with theinvention (in a 30-minute test) out 25 percent better than the control.Moreover, the wheel weight loss (shed) was 48 percent less than in thecontrol wheel.

As many different embodiments of my invention will occur to thoseskilled in the coated abrasive art, it is to be understood that thespecific embodiments of the invention as presented herein are intendedby way of illustration only and not limiting on the invention but thatthe limitations thereon are to be determined only from the appendedclaims.

What I claim is:

1. Abrasive wheel comprising aplurality of flexible coated abrasivesegments each of which has a working edge and a base edge, said segmentsbeing disposed in annular fashion defining by said base edges an innercylindrical periphery and by said working edges an outer cylindricalperiphery, said segments being paired together in interlockingrelationship whereby to create in said pairs a base edge combinedthickness less than the sum of the individual thicknesses of thesegments, and being secured together at said base edges by a curedadhesive.

2. Abrasive wheel according to claim 1 wherein in said interlockingpairs one of said segments has at least one cutout portion extendingradially from sald inner perlphery and the other of said segments has atleast two spaced-apart cutout portions extending radially from the innerperiphery, said spaced-apart cutout portions defining a tablike portion,said one cutout portion matching with the tablike portion whereby thesegments are interlocked thus permitting a greater number of totalsegments to be provided in the abrasive wheel than in a wheel havingsegments not possessing such cutout and tablike portions.

3. Abrasive wheel according to claim 2 wherein said at least one cutoutportion and said tablike portion are widest at the base edge of thesegment and narrowest at some distance from said base edge.

4. Abrasive wheel according to claim 3 wherein in each of said segmentshaving at least one cutout portion is located at a distance from thebase edge opposed notches, said notches forming in said abrasive wheelannular grooves concentric with said inner cylindrical periphery, saidat least one cutout portion extending to a distance no greater than animaginary line connecting together said notches at their center.

5. Abrasive wheel according to claim 4 wherein in the other of saidsegments said spaced-apart cutout portions extends to a distance fromthe base edge no farther than does said at least one cutout portionextend from its base edge.

6. Abrasive wheel according to claim 5 wherein the segments have cutoutportions and tablike portions such as shown in FIGS. 2 and 3.

7. Abrasive wheel according to claim 2 wherein said at least one cutoutportion is defined by a bottom edge parallel to the base edge of thesegments, spaced-apart side edges extending perpendicularly therefromfor some distance toward the base edge and which taper outwardly at adistance more closely adjacent said base edge and said tablike portionin the other se ment is defined by a complementing shape.

1. Abrasive wheel comprising a plurality of flexible coated abrasivesegments each of which has a working edge and a base edge, said segmentsbeing disposed in annular fashion defining by said base edges an innercylindrical periphery and by said working edges an outer cylindricalperiphery, said segments being paired together in interlockingrelationship whereby to create in said pairs a base edge combinedthickness less than the sum of the individual thicknesses of thesegments, and being secured together at said base edges by a curedadhesive.
 2. Abrasive wheel according to claim 1 wherein in saidinterlocking pairs one of said segments has at least one cutout portioNextending radially from said inner periphery and the other of saidsegments has at least two spaced-apart cutout portions extendingradially from the inner periphery, said spaced-apart cutout portionsdefining a tablike portion, said one cutout portion matching with thetablike portion whereby the segments are interlocked thus permitting agreater number of total segments to be provided in the abrasive wheelthan in a wheel having segments not possessing such cutout and tablikeportions.
 3. Abrasive wheel according to claim 2 wherein said at leastone cutout portion and said tablike portion are widest at the base edgeof the segment and narrowest at some distance from said base edge. 4.Abrasive wheel according to claim 3 wherein in each of said segmentshaving at least one cutout portion is located at a distance from thebase edge opposed notches, said notches forming in said abrasive wheelannular grooves concentric with said inner cylindrical periphery, saidat least one cutout portion extending to a distance no greater than animaginary line connecting together said notches at their center. 5.Abrasive wheel according to claim 4 wherein in the other of saidsegments said spaced-apart cutout portions extends to a distance fromthe base edge no farther than does said at least one cutout portionextend from its base edge.
 6. Abrasive wheel according to claim 5wherein the segments have cutout portions and tablike portions such asshown in FIGS. 2 and
 3. 7. Abrasive wheel according to claim 2 whereinsaid at least one cutout portion is defined by a bottom edge parallel tothe base edge of the segments, spaced-apart side edges extendingperpendicularly therefrom for some distance toward the base edge andwhich taper outwardly at a distance more closely adjacent said base edgeand said tablike portion in the other segment is defined by acomplementing shape.